SSN Format Validator (Structure Check)
Paste a US Social Security Number to check its structure against the published formatting rules. The tool splits out the area, group and serial parts and flags the combinations that can never be valid. It checks format only and never looks up a person.
How to check an SSN format
- Type or paste the SSN as nine digits or in AAA-GG-SSSS form.
- See the valid or invalid badge update with the specific reason.
- Review the area, group and serial breakdown, then copy the formatted value.
Examples
A structurally valid SSN
123-45-6789
valid: true, area: 123, group: 45, serial: 6789
An invalid area number
666-12-3456
valid: false, reason: area cannot be 666
Frequently asked questions
Does this confirm an SSN belongs to a real person?
No. This tool checks structural validity only. It applies the published formatting rules to flag numbers that can never be issued, but it cannot tell you whether a well-formed number was actually assigned to anyone. Only the Social Security Administration can confirm that.
Which SSN formats are accepted as input?
You can enter nine bare digits, or the grouped AAA-GG-SSSS form using hyphens or spaces between the three parts. Letters or other separators are treated as invalid. Whichever form you use, the result is shown in the standard hyphenated format.
What combinations make an SSN structurally invalid?
An SSN is never valid if the area (first three digits) is 000, 666, or in the 900-999 range, if the group (middle two digits) is 00, or if the serial (last four digits) is 0000. The validator reports exactly which of these rules a number breaks.
Why are numbers starting with 9 rejected?
The 900-999 area range is not used for Social Security Numbers. Numbers in that range are instead used for Individual Taxpayer Identification Numbers (ITINs), which are a separate identifier, so they are not valid SSNs.
Is my SSN sent anywhere or stored?
No. All validation runs locally in your browser using client-side JavaScript. The number you enter is never uploaded, logged, or stored, so it never leaves your device.
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